Casino sites are doing well. The only thing which slows down earnings for me is that some of my players are winning constantly and this affects my earnings ofcourse. But I am happy so far. It is correct US players and Canadian players can not withdraw that easy so they might stop playing at a certain time.
On the other hand maybe your players need to cool off for a while before they play again. I see this a lot.
If you have “heavy” gamblers they might have found other casinos to gamble. I do not like those more experienced players because they can easily put your monthly earnings down the drain. “keep it slow but steady” 
Good Luck
Regards
Rick